Ught-beactive besistance and method



T. W. CASE.

LlGH REACTIVE RESISTANCE AND METHOD 0F FORMIN'G SAME.

APPLICATION FILED APR.5.19|8.

l ,3 l 59.350. Patented Sept.. 16, 1919.

THEODORE W. GASE, 0l' SCIPIO, NEW YORK.

LIGHT-REACTIVE BESISTAN CE AND METHOD OF FOBMING SAME.

Specication of Letters Patent.

Patented Sept. 16, 1919.

Application led April 5, 1918. Serial No. 226,906.

To all whom t may concern.'

Be it known that I, Trmonoim W. Caen, a citizen of the United States of America, and resident of Scipio, in the county of Cayuga, in the State of NewYork, have invented new and useful Improvements in Light-Reactive Resistances and Methods of Forming Same, of which the following, taken in connection with the accompanying drawings, is a full, clear, and exact description.

This invention relates to certain new and novel light reactive resistance elements and to the materials from which the same are formed .and the method of forming the same and incertain respects is closely related to my copending application Ser. No. 195,653.

As illustrative of one particular use for which my invention is specially adapted,

reference is hereby made to my copending applications, Ser. Nos. 213,225 and 218,308 respectively.

I have discovered that a material comprising or consisting of an oxidized com pound of thallium and sulfur can be utilized as a portion of an electric circuit and that its resistance to the passage of current through said circuit varies under the iniiuence of light to effect a change of current in accordance with the intensity of the light rays to which the substance is subjected `and that a thallium-oxy-suliid is considerably more sensitive than an unoxidized compound of thallium and sulfur.

The oxidation ma be effected in any suitable way as for instance by admitting a desired quantity of air to a vacuum vessel in which the thallium-sulfid may be dried after precipitation. The compound seems to assume its most sensitive form when only slightly oxidized. I desire therefore, to claim thallium-oxy-suld as a light reactive resistance.

I have further discovered that the physical character or structure of the resistance element whether formed of the materials named or of other materials as set forth in my @pending applicatie@ .Set Nos, 195,653-1.-

ltially uniform character.

169,111--149,70414:9,705 and 195,652 1'0- speotively has a very material and impor# tant bearing upon the sensitiveness of the resistance material. In mypresent method of manufacturing such element I provide a suitable supportin member for the resistance material.

at lpresent to prefer for this pur a disk of quartz or silica which material may be.

subjected to relatively high temperature without change and without chemically varying the material of which the resistance element is formed. At any rate such a substance should be -used as will not either in hea-ted or unheated condition chemically vary the material of which the resistance element is to be formed as for instance, by absorbing sulfur from thallium-oxy-suld or vary or change in any harmful way'the composite body of resistance material or any element thereof.

This disk is heated in any suitable way to such a temperature that the material from which the element is to be formed melts or partially'` melts or coalesces so that it is easily spread in a layer on a surface of the disk to' form a unitary body of substan- It will be apparent that this coalesced layer of light reactive material may be formed upon the disk in various ways as for instance by heating the disk to such a temperature that when the material comes in contact with the surface thereof, it is melted or fused or partially fused to a predetermined extent as desired, or the material and the disk may be heated in unison to effect the desiral melting or fusion of the light reattive material without affecting the disk. The fused, partially fused or melted material may be spread in any 'suitable way upon the disk and is preferably immediately and rapidly cooled after proper formation of the layer.

Various materials require the application of various temperatures to effect the desired .coalescence These temperatures can be ad-l vantageously determined empirical] in accordance withthe material used an the 0pr/tlng conditions,

y experience leads me or silica havin In the use of thallium-oxy-suld the temperature may vary greatly as from 450 C. to 700 C. or perhaps to a greater extent depending considerably upon the degree o f oxidation and my experience at present 1s that oxidation has been carried to the most eicient extent when the required fusing or coalescence of the material is effected in the desired manner at approximately a temperature of 650 C.l

In the drawings hereto annexed Figure 1 is a plan view of a resistance element or cell.

Fig. 2 is across-section on line 2-2 Fig. 1 showing the resistance element proper in resistance element proper.

' Fig. 4 is a plan view of a slightly different form of resistance element.

The resistance element or cell as shown. in the drawing comprises a supporting disk or block 1 of suitable material as quartz formed thereon a la er -2- of suitab e light reactive materlal.'

As shown in Figs. -1-, -2-, and -3 the layer` v-2- is provided with suitable gold leaf or other suitable material preferably covering a portion of the surface of the layer -2 and leaving other portions 6 and -7 uncovered for exposure to light rays. The contacts may extend over the edges of layer 2- and block -1- and contacts -3- and -5- mayl be connected in series in any suitable way as by conductor sired practically all air may be removed.,

When so inclosed the element is found to be more permanent in its physical and chemical nature, more sensitive in its action and practically uniform in such action for long periods of time. The permanency of the element may be somewhat attributed to the absence of moisture but the reasons wh the element when so inclosed has the a vantageous character described has not as yet been so definitely and accurately deternined that itcan be stated with assurety and positiveness and I am therefore content with the statement that such results are effected. Al-I though the `side -12- of vessel -11- i lium-suld slightly removed.

through which the light reactive material is exposed may as shown be perfectly flat yet it will be apparent that, lenticular power may be given to this surface for concentrating the rays of light upon the resistance, should that be desired. v

The construction shown in Fig 4 is substantiall the same as that shown in the former gures except that only two contacts 13 and 111- are used which contacts are separated by a single strip 15 of exposed light reactive material.

Although I have described certain structures and methods of producing the same as in my present experience highly eflicient and perhaps preferable, I do not desire to limit myself to the same as various changes and modifications may be made without departing from the spirit of this invention as set forth in the appended claims.

What I claim is:

1. vA resistance material comprising thal lium-oxy-suld.

2. A resistance material formed of thallium-oxy-suld.

3. A resistance material comprising thaloxidized.

4. A light-reactive resistance including a fused coherentl body comprising thalliumoxy-sulfid.

5. A light-reactive resistance comprising a disk, a layer of coalesced light-reactive maferial on the disk, contacts partially covering the surface of the light-reactive material and spaced from each other.

' 6. A light-reactive resistance comprising a disk of material, of high silica content, a layer of coalesced light-reactive material on the disk, contacts partially covering the surfacel of the light-reactive material and spaced from each other.

7. The method'of forming a light-reactive resistance comprising heatin the resistance material to substantially a fgusing temperature, shaping the heated material into a uni form layer, and immediately cooling the layer. y

8. The method of forming a light-reactive resistance comprising heatlng a light-reactive material in contact with a supporting element, forming said material in a layer upon said element, and spreading contacts in spaced strips upon the surface of said ayer.

9. The method of forming a light-reactive resistance comprising heating a light-reactive material in contact with a supporting element, forming said material in a layer upon said element, spreading contacts in spaced strips upon said layer, and inclosing said element in an air-tight vessel from which the moisture has been substantially 10. .A light reactive resistance element comprising a supporting disk, a layer of In witness whereof I have hereunto set light', reacptlve material thereon and strips of my hand this 15th day ofMarch, 1918.

material spread upon the surface of said layer and spaced from each other and con- THEODORE W' CASE' stltuting contacts. Witnesses:

11. A resistance material comprising thal- EARL I. SPONABLE,

lium-oxy-suld under vacuum. Buss S. CUSHM'AN. 

